CA1217361A - Alloy and process for producing ductile and compacted graphite cast irons - Google Patents
Alloy and process for producing ductile and compacted graphite cast ironsInfo
- Publication number
- CA1217361A CA1217361A CA000424042A CA424042A CA1217361A CA 1217361 A CA1217361 A CA 1217361A CA 000424042 A CA000424042 A CA 000424042A CA 424042 A CA424042 A CA 424042A CA 1217361 A CA1217361 A CA 1217361A
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- Prior art keywords
- iron
- alloy
- magnesium
- carbon
- weight
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Classifications
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C37/00—Cast-iron alloys
- C22C37/04—Cast-iron alloys containing spheroidal graphite
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C1/00—Refining of pig-iron; Cast iron
- C21C1/10—Making spheroidal graphite cast-iron
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C33/00—Making ferrous alloys
- C22C33/08—Making cast-iron alloys
- C22C33/10—Making cast-iron alloys including procedures for adding magnesium
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- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Mechanical Engineering (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
ALLOY AND PROCESS FOR PRODUCING DUCTILE
AND COMPACTED GRAPHITE CAST IRONS
Abstract of the Disclosure The present invention is directed to an alloy composition and the method of treating molten cast iron with such alloy to produce ductile and compacted graphite cast irons. The alloy may contain about 0.1% to about 10% silicon, about 0.05 to about 2.0%
cerium and/or other rare earth elements, about 0.5 to about 4%
magnesium, about 0.5 to about 6.5% carbon (percent by weight) the balance being iron.
AND COMPACTED GRAPHITE CAST IRONS
Abstract of the Disclosure The present invention is directed to an alloy composition and the method of treating molten cast iron with such alloy to produce ductile and compacted graphite cast irons. The alloy may contain about 0.1% to about 10% silicon, about 0.05 to about 2.0%
cerium and/or other rare earth elements, about 0.5 to about 4%
magnesium, about 0.5 to about 6.5% carbon (percent by weight) the balance being iron.
Description
736~
ALLOY AND PROCESS FOR PRODUCI~G 3IJCTILE
AND COMPACTED GRAPHITE CAST I~O~IS
This invention relates to an alloy of exce~tional utility for producing ductile cast iron or compacted graphîte cast irons and the process of treating cast iron with said alloy. The alloy comprises a low silicon, low magnesium predominately iron alloy containing rare earth elements such as cerium as the essential elements.
It is kn-own to introduce magnesium in controlled quantities into a melt of ordinary gray cast iron in order to cause the carbon to solidify in a spheroidal form and thereby produce ductile cast iron with greatly imp~oved tensile strength and ductility over that exhibited by ordinary cast iron. The amount of magnesium retained in the melt for this purpose varies but in general will range from about .0~% to about .08% magnesium by weight of iron depending on the composition or the iron melt at hand.
Compacted graphite cast iron, also known as vermicular graphite iron is also produced by addition of magnesium. In this case the carbon precipitates in a form more rounded and ;ome~,Jhat chunky and stubby as compared to normal flake graphite co~only found in gray cast iron. The amount of magnesium retained in the moltén iron is carefully controlled to provide from about .015~ to about .035%
magnesium by weight of iron and again the exact mount depends on the particular composition of the molten iron and other kno~m foundry variables. In general, compacted graphite cas~ iron has a measure of the strength characteristics of ductile iron ~nd possesses greater thermal conductivity and resistance to thermal ~ock, 736~
The production o~ duc~ile cast iron and compdcted graph-ite CdSt irons is well known and as is known, dif~iculties are encountered by virtue of the pyrotechnics that occur ~I;,en magnesium is added to molten iron. The molten iron bath fumes, smokes and flares with resulting uneconomical loss of magnesium, air pollution and difficult~
in controlling the addition of measured amounts o~ magnesium to the molten iron for the desired result.
Thes~ problems exist when a conventional ferrosilicon a~loy contain-ing five percent or more of magnesium is used. (U.S. Patents 3,177,071;
3,367,771 and 3,375,104). Suggestions have been made to oYercome the drawback o~ the magnesium ferrosilicon alloyc. by using high nickel alloys (U.S. Patents 3,030,205; 3,544,312); by using coke or charcoal impregnated with magnesium (U.S. Patents, 3,321,304; 3,598,572; 4,003,424); or by using briquettes and compacted particulate metals (U.S. Patents 3,2gO,142;
4,309,216 and UK Patents 1,397,600; ?,066,297?.
High nickel alloys are expensive and are not generally used except in those limited circumstances where a high nickel cast iron is desired.
Coke and charcoal impregnated with magnesium and briquettes and compacted particular metals can assist somewhat in solving the pyrotechnical problem but these materials require special handling techniques and apparatus which only serve to increase cost and add to the requirement for sophisti cated controls.
Mechanical approaches have also been used ~herein a magnesium composi-tion is introduced below the surface of the molten iron bath (U.S. Paten~s
ALLOY AND PROCESS FOR PRODUCI~G 3IJCTILE
AND COMPACTED GRAPHITE CAST I~O~IS
This invention relates to an alloy of exce~tional utility for producing ductile cast iron or compacted graphîte cast irons and the process of treating cast iron with said alloy. The alloy comprises a low silicon, low magnesium predominately iron alloy containing rare earth elements such as cerium as the essential elements.
It is kn-own to introduce magnesium in controlled quantities into a melt of ordinary gray cast iron in order to cause the carbon to solidify in a spheroidal form and thereby produce ductile cast iron with greatly imp~oved tensile strength and ductility over that exhibited by ordinary cast iron. The amount of magnesium retained in the melt for this purpose varies but in general will range from about .0~% to about .08% magnesium by weight of iron depending on the composition or the iron melt at hand.
Compacted graphite cast iron, also known as vermicular graphite iron is also produced by addition of magnesium. In this case the carbon precipitates in a form more rounded and ;ome~,Jhat chunky and stubby as compared to normal flake graphite co~only found in gray cast iron. The amount of magnesium retained in the moltén iron is carefully controlled to provide from about .015~ to about .035%
magnesium by weight of iron and again the exact mount depends on the particular composition of the molten iron and other kno~m foundry variables. In general, compacted graphite cas~ iron has a measure of the strength characteristics of ductile iron ~nd possesses greater thermal conductivity and resistance to thermal ~ock, 736~
The production o~ duc~ile cast iron and compdcted graph-ite CdSt irons is well known and as is known, dif~iculties are encountered by virtue of the pyrotechnics that occur ~I;,en magnesium is added to molten iron. The molten iron bath fumes, smokes and flares with resulting uneconomical loss of magnesium, air pollution and difficult~
in controlling the addition of measured amounts o~ magnesium to the molten iron for the desired result.
Thes~ problems exist when a conventional ferrosilicon a~loy contain-ing five percent or more of magnesium is used. (U.S. Patents 3,177,071;
3,367,771 and 3,375,104). Suggestions have been made to oYercome the drawback o~ the magnesium ferrosilicon alloyc. by using high nickel alloys (U.S. Patents 3,030,205; 3,544,312); by using coke or charcoal impregnated with magnesium (U.S. Patents, 3,321,304; 3,598,572; 4,003,424); or by using briquettes and compacted particulate metals (U.S. Patents 3,2gO,142;
4,309,216 and UK Patents 1,397,600; ?,066,297?.
High nickel alloys are expensive and are not generally used except in those limited circumstances where a high nickel cast iron is desired.
Coke and charcoal impregnated with magnesium and briquettes and compacted particular metals can assist somewhat in solving the pyrotechnical problem but these materials require special handling techniques and apparatus which only serve to increase cost and add to the requirement for sophisti cated controls.
Mechanical approaches have also been used ~herein a magnesium composi-tion is introduced below the surface of the molten iron bath (U.S. Paten~s
2,869,857; 3,080,228; 3,157,492; 3,285,739; 4,147,533; 4,166,738). While this is of help, substantial quantities of ma~nesium are nevertheless lost to the atmosphere and in many cases the 3dded steps incident to the mechanical approach do not adequately compensate for the loss of magnesium.
~361 In accortlance wi-th tne presen-t invention, an ~lloy o-F exceptional utility has been devised for producing ductile and compacted graphite cast irons which makes it possible to virtually eliminate the pyrotechni-cal problem heretofore experienced in the art. ,loreover, the alloy of this invention provides a high recovery of magne;iurn and greater flexi-bility in the procedures employed for manufacturing ductile and compacted cast irons. Essentially the alloy may conta;n from about a.l to about lO.O~ silicon, about - 0.05 to about 2.0% cerium and/or one or more other rare earth elements, ahout 0.5 to about 4.0% magnesium, about 0.5 to about 6.5% carbon. All percentages are based on the weight of the alloy, the balance being iron. The alloy may contain small amounts of other elements such as calcium, barium or strontium and trace elements conven-tionally present in the raw materials used in producing the alloy will also be present.
The very low amount of silicon in the alloy is of particular advantag~
in that scrap metals of relatively high silicon content may be used in the cast iron melt, and thereby provide the final product with a commercially acceptable level of silicon. Excess silicon in 'he final ductile or com-pacted graphite cast ;ron tends to give the iron low impact characteristics which are undesirable in most applications. The low silicon content of the alloy of the present invention is of further advantage for increasing the density of the alloy which reduces the tendency to float with a con-current reduction in pyrotechnics and increased recovery of magnesium in the molten iron. Conventional magnesium alloys containing twenty five and more percent by weight of silicon having a densit~ of about 3.5 to about 4.5 gms/cm3 do not give the advantages and flexibility of the low silicon alloy of the present invention.
The low magnesium content of the alloy of tnis invention materially contributes to a high recovery of magnesiunl in tre treated molten cast iron and a highly desirable reduction in pyrotecnnics The high and consistent recoveries resulting frorn the low magnssillm content of the alloy also facilitates control of the amount of magnesium retainetl in the melt which assists in providiny the proper amourlt of m;lgllPsium within tht!
narrow range required to produce compac'ed gra~ 1e Cdst irons~
.
~Z1736~ .
The cerium and/or ot~ler rare earth elemenls con-tent o~ the alloy is essential to counteract the deleterious effect of tramp elements such as lead, bismuth, titanium and antimony which tend to inhibit nodulization of graphite that precipitates from the melt for production of ductile cast iron. The cerium and/or other rare earth elements are also important for their nucleating and nodulizing effects in the melt and tendency to reduce the formation of undesirable carbides in ductile cast iron. Cerium is the preferred rare earth element.
Best results are achieved when the density of the alloy of the present invention ;s from about 6.5 to about 7.5 gms./cm3 and contains from about 1.0 to about 6% silicon, about 0.2 to 2.0% cerium and/or one or more rare earth elements, about 0.9 to 2~0% magnesium, about 3.0 to about 6.0% carbon (by weight of alloy), the balance being iron containing small amounts of other elements as described herein above. Within the specified range of density, there is a reduced tendency for the alloy to float on the surface of the treated molten cast iron which in general has a density of about 6.0 to 6.5 gms/cm3 depending on composition and temperature. This is of advantage to reduce pyrotechnics and increase recovery of magnesium in the melt.
The alloy of the present invention may be made in conventional manner with conventional raw materials known in the art. In a preferred procedure, the vessel in which the alloy is formed is held under the pressure of an inert gas such as argon at about 50 to 75 p.s.i.g. Conventionally available magnesium scrap, magnesium silicide, and magnesium metal may be used in forming the alloy. The rare earth elements may be introduced as elements per se into the alloy, or mischmetal may be employed, or cerium metal, or cerium silicides may be used. Silicon metal, ferrosilicon, ;ilicon carbide, carbon, and ordinary pig iron or steel scrap ,nay be used in producing the alloy. The amounts of raw materials are controlled in known nanner to forrn an alloy within tl1e specified range of elemen~ est resul~s are acilie~ed by rapid solidification of the alloy malt~
~736~
In one example, the alloy of the present inverltion was produced by charging 572.0 grams of CSF No. 10 (Foote Mineral), and 88 grams of magnesium metal, and iron, into a vessel and heating to 1300C while held under argon gas pressure of 60 p.s.i.g. The melt was held for three minutes and the total charge of 6000 grams was thereupon rapidly solidi-fied as by a chill mold technique. The resulting iron alloy by analysis contained 1.24% by weight of magnesium and 0.97% by weight of cerium and a low silicon content with;n the specified range. The CSF No. 10 is the trade ~a~ of Foote Minerals Company for an iron alloy containing about 38% silicon, about 10% cerium and about 2% other rare earth elements (total 12~o rare earth elements) by weight, the balance of the alloy being iron.
The procedure o~ E~ample 1 was aga;n used to produce the low silicon predominately iron alloy of the present invention using a total charge of 6000 grams containing iron and the following added materials.
Charge in Grams Alloy Analysis CSF 10 M~ % Mg % Ce 450 90 1.17 0.66 300 90 1.04 0.48 As a result of rapid solidification, the magnesium in the alloy of the present invention is retained as a fine dispersion or separate phase within the iron-carbon silicon matrix. Since the magnesium exists as a fine dispersion in the alloy, the interaction between the magnesium and the molten cast iron being treated in the foundry takes place at a multi-tude of locations. The advantage of such a dissolution of magnesium in the foundry melt is that a higher recovery of magnesium in the treated cast iron is achieved as compared to conventional magnesium ferrosilicon alloys.
Any desired procedure may be used in treating molten cas-t iron with the alloy of the present invention to produce ductile or compacted graphite cast irons such as the known sandwich method, pour-over technique, positioning the alloy within a reaction chamher inside the mold, adding the alloy to a stream of molten cast iron or to a bath oF molten cast iron in a furnace or foundry ladle. The allo~ may be introduced into *trade mark ~'J ~ b~
~73~
the molten cast iron to be treated in molten form under pressure or solid particulate form or as bars or ingots and the like depending on the foundry process at hand. The amount of alloy added to the cast iron to be treated may be varied in known manner depending on the selected composition for the final product. In general, the amount of alloy added to molten cast iron is sufficient to retain from about .015 to .035% magnesium by weight of the treated iron to produce compacted graphite cast irons and from about .02% to about .08% by weight for ductile iron with nodular carbon. The exact level of magnesium in the treated molten iron may be determined by conventional foundry analysis. Because of the high magnesium recovery obtained by the alloy of the present invention in the treated metal, a smaller amount of the magnesium may be added to achieve the selected composition for the final product as compared to the customary alloys conventionally used. For example, 38.0 kilograms of conventional foundry cast iron was treated with the alloy of the present invention to produce ductile cast iron bg plunging the .
following particulate mixture beneath the surface of a molten iron bath at a temperature of 1525C:
Alloy Elemental % by Wei~ht Amount in Mix Heat No. M~. Ce C Si Fe Grams 214 1.34 0.65 3.22 4.60 Remainder 902 216 1.32 0.61 3.45 3.78 Remainder 902 The molten cast iron into which the above mixture was plunged contained 3.67% carbon, 2.01% silicon and mls/~
~2:L736~
0.019% sulfur based on the weight o~ the cast iron. There were no deleterious pyrotechnics and when the reaction was deemed to be completed 7.0 kilograms of molten treated iron were tapped into a foundry ladle. The 7.0 kilograms were inoculated in conventional manner by stirring in foundry grade 75% ferrosilicon in an amount sufficient to bring the silicon content of the treated molten iron up to about 2.5%
by weight.
A sample of the resulting ductile iron, after complete dissolution of the ferrosilicon, was analyzed to determine the percent by weight of magnesium, silicon and cerium and the percent by weight of magnesium recovered in the treated molten iron compared to the magnesium input from the alloy used in treating the iron as follows:
Allov Input Iron Analvsis ~eat % MR % Si % M~ % Si % MR Recovered J882 0.06 0.2 0.038 2.51 63 Recovery in the molten iron of 63% by weight of the magnesium available in the alloy is exceptional as compared to a recovery of only ~bout 22% to 28% magnesium from a magnesium ferrosilicon alloy containing 5% magnesium when the molten iron was treated in the same manner. In addition, one would expect an increase in the silicon content of the molten iron on the order of about 1.2% resulting from use of conventional magnesium ferrosilicon alloys.
A quantitative metallographic analysis of the polished surface of fins cut from a cast specimen of the melt was as follows:
~736i Fin Thickness (cm) % Nodularity Nodules/mm2 0.6 91 351 1.9 85 236 The percent nodularity and nodule count were as expected for ductile iron castings.
Additional examples of iron alloys made in accordance with the present invention had the following chemical analyses of essential elements, in percent by weight:
Elemental % b~ Weight Alloy M~ Ce C Si Fe Run 177 1.23 O.Sl 3.32 5.72Balance Run 178 1.34 0.86 2.86 7.16Balance Run 178 1.22 0.48 4.25 2.45Balance Run 180 1.48 0.85 4.06 3.76Balance In all cases the alloys contained small amounts of other elements.
The foregoing alloys were used in treating molten iron containing the following essential elements in percent by weight and small amounts of other elements conventionally present in iron:
Element % bv Wei~ht Heat C Si Mn S Fe J 694 3.42 2.11 0.52 0.011Balance J 695 3.76 2.11 0.53 0.009Balance J 696 3.78 2.16 0.52 0.010Balance J 697 3.86 2.17 0.53 0.010Balance The treatment was carried out by pouring molten iron at a temperature of 1525C over a preweighed quantity of alloy lying in a treatment pocket at the bottom of a foundry ladle. After the reaction had subsided, seven kilograms molten cast iron were transferred to a 10 kg capacity clay graphite crucible. When the temperature of the molten iron in that crucible dropped to 1350C, a foundry grade 75%
ferrosilicon was stirred into the bath as a post inoculant in an amount sufficient to increase the silicon content of molten iron to about 2.7% by weight. Samples of iron were taken from the melt for analysis and specimen castings with fins 0.6 cm and 1.9 cm thic~ were poured after the temperature of the treated metal had dropped to 1325C.
The weight of alloy used in treating the molten iron was in each case calculated for a selected percent of input of magnesium based on the weight of molten iron to be treated. The molten iron treated with the following input of magnesium contained the following essential elements in percent by weight with the specified recovery of magnesium and cerium:
Treated Iron AnalYsis Recovered Alloy % Mg Heat Used Input % C % Si % M~ % Ce% M~
J 694 177 0.060 3.56 2.70 0.048 0.03380 J 695 178 0.060 3.58 2.76 0.043 0.03072 J 696 179 0.060 3.56 2.12 0.042 0.02370 J 697 180 0.060 3.76 2.65 0.034 0.02857 - 8a -~;~73~ I
A quantita~ive metallograp~ic anal~sis of the polished surface ol~
fins cut from a cast specimen o~ the melt was as ~ollows: 3 Fin Thickness - % Nodules/
Heat cm Nodularity mm2 J 694 0.6 cm 93 458 J 694 1.9 cm 90 224 ~ 695- 0.6 cm 92 369 J 695 1.9 cm 85 170 J 696 0.6 cm 94 449 J 696 1.9 cm 82 186 7 0.6 cm 91 430 J ~37 1.9 cm 80 141 As i; conventional in the art, the treated molten cast iron may be inoculated with a ferrosilicon composition to reduce the formation of iron carbides (~.S. Patent 4,224,064). If desired for a particular ductile or compacted graphite cast iron composition, one or more other metals may be incorporated into the alloy of the present invention which in some cases may be of advantage to avoid the separate addition of such metals to the molten cast iron. One or more other metals which may have a desired effect with respect to the formation of ductile or compacted graphite cast irons or a desired effect on the physical properties of the final product may also be incorporated into the alloy of the present invention.
It will be understood that it is intended to cover all changes and modifications of the preferred form of invention herein chosen for the purpose of illustration which do not depart from the spirit and scope of the invention.
~361 In accortlance wi-th tne presen-t invention, an ~lloy o-F exceptional utility has been devised for producing ductile and compacted graphite cast irons which makes it possible to virtually eliminate the pyrotechni-cal problem heretofore experienced in the art. ,loreover, the alloy of this invention provides a high recovery of magne;iurn and greater flexi-bility in the procedures employed for manufacturing ductile and compacted cast irons. Essentially the alloy may conta;n from about a.l to about lO.O~ silicon, about - 0.05 to about 2.0% cerium and/or one or more other rare earth elements, ahout 0.5 to about 4.0% magnesium, about 0.5 to about 6.5% carbon. All percentages are based on the weight of the alloy, the balance being iron. The alloy may contain small amounts of other elements such as calcium, barium or strontium and trace elements conven-tionally present in the raw materials used in producing the alloy will also be present.
The very low amount of silicon in the alloy is of particular advantag~
in that scrap metals of relatively high silicon content may be used in the cast iron melt, and thereby provide the final product with a commercially acceptable level of silicon. Excess silicon in 'he final ductile or com-pacted graphite cast ;ron tends to give the iron low impact characteristics which are undesirable in most applications. The low silicon content of the alloy of the present invention is of further advantage for increasing the density of the alloy which reduces the tendency to float with a con-current reduction in pyrotechnics and increased recovery of magnesium in the molten iron. Conventional magnesium alloys containing twenty five and more percent by weight of silicon having a densit~ of about 3.5 to about 4.5 gms/cm3 do not give the advantages and flexibility of the low silicon alloy of the present invention.
The low magnesium content of the alloy of tnis invention materially contributes to a high recovery of magnesiunl in tre treated molten cast iron and a highly desirable reduction in pyrotecnnics The high and consistent recoveries resulting frorn the low magnssillm content of the alloy also facilitates control of the amount of magnesium retainetl in the melt which assists in providiny the proper amourlt of m;lgllPsium within tht!
narrow range required to produce compac'ed gra~ 1e Cdst irons~
.
~Z1736~ .
The cerium and/or ot~ler rare earth elemenls con-tent o~ the alloy is essential to counteract the deleterious effect of tramp elements such as lead, bismuth, titanium and antimony which tend to inhibit nodulization of graphite that precipitates from the melt for production of ductile cast iron. The cerium and/or other rare earth elements are also important for their nucleating and nodulizing effects in the melt and tendency to reduce the formation of undesirable carbides in ductile cast iron. Cerium is the preferred rare earth element.
Best results are achieved when the density of the alloy of the present invention ;s from about 6.5 to about 7.5 gms./cm3 and contains from about 1.0 to about 6% silicon, about 0.2 to 2.0% cerium and/or one or more rare earth elements, about 0.9 to 2~0% magnesium, about 3.0 to about 6.0% carbon (by weight of alloy), the balance being iron containing small amounts of other elements as described herein above. Within the specified range of density, there is a reduced tendency for the alloy to float on the surface of the treated molten cast iron which in general has a density of about 6.0 to 6.5 gms/cm3 depending on composition and temperature. This is of advantage to reduce pyrotechnics and increase recovery of magnesium in the melt.
The alloy of the present invention may be made in conventional manner with conventional raw materials known in the art. In a preferred procedure, the vessel in which the alloy is formed is held under the pressure of an inert gas such as argon at about 50 to 75 p.s.i.g. Conventionally available magnesium scrap, magnesium silicide, and magnesium metal may be used in forming the alloy. The rare earth elements may be introduced as elements per se into the alloy, or mischmetal may be employed, or cerium metal, or cerium silicides may be used. Silicon metal, ferrosilicon, ;ilicon carbide, carbon, and ordinary pig iron or steel scrap ,nay be used in producing the alloy. The amounts of raw materials are controlled in known nanner to forrn an alloy within tl1e specified range of elemen~ est resul~s are acilie~ed by rapid solidification of the alloy malt~
~736~
In one example, the alloy of the present inverltion was produced by charging 572.0 grams of CSF No. 10 (Foote Mineral), and 88 grams of magnesium metal, and iron, into a vessel and heating to 1300C while held under argon gas pressure of 60 p.s.i.g. The melt was held for three minutes and the total charge of 6000 grams was thereupon rapidly solidi-fied as by a chill mold technique. The resulting iron alloy by analysis contained 1.24% by weight of magnesium and 0.97% by weight of cerium and a low silicon content with;n the specified range. The CSF No. 10 is the trade ~a~ of Foote Minerals Company for an iron alloy containing about 38% silicon, about 10% cerium and about 2% other rare earth elements (total 12~o rare earth elements) by weight, the balance of the alloy being iron.
The procedure o~ E~ample 1 was aga;n used to produce the low silicon predominately iron alloy of the present invention using a total charge of 6000 grams containing iron and the following added materials.
Charge in Grams Alloy Analysis CSF 10 M~ % Mg % Ce 450 90 1.17 0.66 300 90 1.04 0.48 As a result of rapid solidification, the magnesium in the alloy of the present invention is retained as a fine dispersion or separate phase within the iron-carbon silicon matrix. Since the magnesium exists as a fine dispersion in the alloy, the interaction between the magnesium and the molten cast iron being treated in the foundry takes place at a multi-tude of locations. The advantage of such a dissolution of magnesium in the foundry melt is that a higher recovery of magnesium in the treated cast iron is achieved as compared to conventional magnesium ferrosilicon alloys.
Any desired procedure may be used in treating molten cas-t iron with the alloy of the present invention to produce ductile or compacted graphite cast irons such as the known sandwich method, pour-over technique, positioning the alloy within a reaction chamher inside the mold, adding the alloy to a stream of molten cast iron or to a bath oF molten cast iron in a furnace or foundry ladle. The allo~ may be introduced into *trade mark ~'J ~ b~
~73~
the molten cast iron to be treated in molten form under pressure or solid particulate form or as bars or ingots and the like depending on the foundry process at hand. The amount of alloy added to the cast iron to be treated may be varied in known manner depending on the selected composition for the final product. In general, the amount of alloy added to molten cast iron is sufficient to retain from about .015 to .035% magnesium by weight of the treated iron to produce compacted graphite cast irons and from about .02% to about .08% by weight for ductile iron with nodular carbon. The exact level of magnesium in the treated molten iron may be determined by conventional foundry analysis. Because of the high magnesium recovery obtained by the alloy of the present invention in the treated metal, a smaller amount of the magnesium may be added to achieve the selected composition for the final product as compared to the customary alloys conventionally used. For example, 38.0 kilograms of conventional foundry cast iron was treated with the alloy of the present invention to produce ductile cast iron bg plunging the .
following particulate mixture beneath the surface of a molten iron bath at a temperature of 1525C:
Alloy Elemental % by Wei~ht Amount in Mix Heat No. M~. Ce C Si Fe Grams 214 1.34 0.65 3.22 4.60 Remainder 902 216 1.32 0.61 3.45 3.78 Remainder 902 The molten cast iron into which the above mixture was plunged contained 3.67% carbon, 2.01% silicon and mls/~
~2:L736~
0.019% sulfur based on the weight o~ the cast iron. There were no deleterious pyrotechnics and when the reaction was deemed to be completed 7.0 kilograms of molten treated iron were tapped into a foundry ladle. The 7.0 kilograms were inoculated in conventional manner by stirring in foundry grade 75% ferrosilicon in an amount sufficient to bring the silicon content of the treated molten iron up to about 2.5%
by weight.
A sample of the resulting ductile iron, after complete dissolution of the ferrosilicon, was analyzed to determine the percent by weight of magnesium, silicon and cerium and the percent by weight of magnesium recovered in the treated molten iron compared to the magnesium input from the alloy used in treating the iron as follows:
Allov Input Iron Analvsis ~eat % MR % Si % M~ % Si % MR Recovered J882 0.06 0.2 0.038 2.51 63 Recovery in the molten iron of 63% by weight of the magnesium available in the alloy is exceptional as compared to a recovery of only ~bout 22% to 28% magnesium from a magnesium ferrosilicon alloy containing 5% magnesium when the molten iron was treated in the same manner. In addition, one would expect an increase in the silicon content of the molten iron on the order of about 1.2% resulting from use of conventional magnesium ferrosilicon alloys.
A quantitative metallographic analysis of the polished surface of fins cut from a cast specimen of the melt was as follows:
~736i Fin Thickness (cm) % Nodularity Nodules/mm2 0.6 91 351 1.9 85 236 The percent nodularity and nodule count were as expected for ductile iron castings.
Additional examples of iron alloys made in accordance with the present invention had the following chemical analyses of essential elements, in percent by weight:
Elemental % b~ Weight Alloy M~ Ce C Si Fe Run 177 1.23 O.Sl 3.32 5.72Balance Run 178 1.34 0.86 2.86 7.16Balance Run 178 1.22 0.48 4.25 2.45Balance Run 180 1.48 0.85 4.06 3.76Balance In all cases the alloys contained small amounts of other elements.
The foregoing alloys were used in treating molten iron containing the following essential elements in percent by weight and small amounts of other elements conventionally present in iron:
Element % bv Wei~ht Heat C Si Mn S Fe J 694 3.42 2.11 0.52 0.011Balance J 695 3.76 2.11 0.53 0.009Balance J 696 3.78 2.16 0.52 0.010Balance J 697 3.86 2.17 0.53 0.010Balance The treatment was carried out by pouring molten iron at a temperature of 1525C over a preweighed quantity of alloy lying in a treatment pocket at the bottom of a foundry ladle. After the reaction had subsided, seven kilograms molten cast iron were transferred to a 10 kg capacity clay graphite crucible. When the temperature of the molten iron in that crucible dropped to 1350C, a foundry grade 75%
ferrosilicon was stirred into the bath as a post inoculant in an amount sufficient to increase the silicon content of molten iron to about 2.7% by weight. Samples of iron were taken from the melt for analysis and specimen castings with fins 0.6 cm and 1.9 cm thic~ were poured after the temperature of the treated metal had dropped to 1325C.
The weight of alloy used in treating the molten iron was in each case calculated for a selected percent of input of magnesium based on the weight of molten iron to be treated. The molten iron treated with the following input of magnesium contained the following essential elements in percent by weight with the specified recovery of magnesium and cerium:
Treated Iron AnalYsis Recovered Alloy % Mg Heat Used Input % C % Si % M~ % Ce% M~
J 694 177 0.060 3.56 2.70 0.048 0.03380 J 695 178 0.060 3.58 2.76 0.043 0.03072 J 696 179 0.060 3.56 2.12 0.042 0.02370 J 697 180 0.060 3.76 2.65 0.034 0.02857 - 8a -~;~73~ I
A quantita~ive metallograp~ic anal~sis of the polished surface ol~
fins cut from a cast specimen o~ the melt was as ~ollows: 3 Fin Thickness - % Nodules/
Heat cm Nodularity mm2 J 694 0.6 cm 93 458 J 694 1.9 cm 90 224 ~ 695- 0.6 cm 92 369 J 695 1.9 cm 85 170 J 696 0.6 cm 94 449 J 696 1.9 cm 82 186 7 0.6 cm 91 430 J ~37 1.9 cm 80 141 As i; conventional in the art, the treated molten cast iron may be inoculated with a ferrosilicon composition to reduce the formation of iron carbides (~.S. Patent 4,224,064). If desired for a particular ductile or compacted graphite cast iron composition, one or more other metals may be incorporated into the alloy of the present invention which in some cases may be of advantage to avoid the separate addition of such metals to the molten cast iron. One or more other metals which may have a desired effect with respect to the formation of ductile or compacted graphite cast irons or a desired effect on the physical properties of the final product may also be incorporated into the alloy of the present invention.
It will be understood that it is intended to cover all changes and modifications of the preferred form of invention herein chosen for the purpose of illustration which do not depart from the spirit and scope of the invention.
Claims (10)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. The method of producing ductile or compacted graphite cast irons which comprises the step of introducing into the molten iron that contains carbon an iron alloy com-prising by weight from about 0.1 to about 10.0% silicon, about 0.05 to about 2.0% of one or more rare earth elements, about 0.5 to about 4.0% magnesium, about 0.5 to about 6.5%
carbon, with the balance of the alloy being iron to increase the magnesium content of said treated molten iron.
carbon, with the balance of the alloy being iron to increase the magnesium content of said treated molten iron.
2. The method of claim 1 in which the one or more rare earth elements is predominately cerium.
3. The method of claim 1 in which the alloy is predominately iron having as essential elements from about 1.0 to about 6.0% silicon, about 0.2 to about 2.0% rare earth elements predominately cerium and about 0.9 to about 2.0%
magnesium by weight of said iron alloy.
magnesium by weight of said iron alloy.
4. The method of claim 3 in which the density of the iron alloy is from about 6.5 to about 7.5 gms/cm3.
5. The method of claim 1 in which the iron alloy is added to the molten iron in an amount sufficient to provide in the molten iron from about .015% to about .08% magnesium based on the weight of the treated molten iron.
6. An iron alloy for treating molten iron containing carbon to produce ductile cast iron containing nodular carbon, or compacted graphite cast iron, said iron alloy comprising by weight from about 0.1 to about 10.0% silicon, about 0.05 to about 2.0% of one or more rare earth elements, about 0.5 to about 4.0% magnesium, about 0.5 to about 6.5%
carbon, the balance of the alloy being iron.
carbon, the balance of the alloy being iron.
7. An alloy for treating molten iron containing carbon to produce ductile cast iron containing nodular carbon or compacted graphite cast iron, said alloy being predominately iron having as essential elements by weight from about 1.0 to about 6.0% silicon, about 0.2 to about 2.0% rare earth elements predominately cerium, about 0.9 to about 2.0%
magnesium, and about 3.0 to 6.0% carbon.
magnesium, and about 3.0 to 6.0% carbon.
8. The alloy of claim 7 having density from about 6.5 to about 7.5 gms/cm.3
9. The method of making an alloy for treating molten iron containing carbon to produce ductile or compacted graphite cast irons which comprises the steps of forming a molten iron bath comprising by weight from about 0.1 to about 10.0% silicon, about 0.05 to about 2.0% one or more rare earth elements, about 0.5 to about 4.0% magnesium, about 0.5 to about 6.5% carbon, the balance being iron and maintaining said molten bath under superatmospheric pressure of an inert gas while reaction takes place and then rapidly solidify-ing the melt to form the iron alloy.
10. The method of making an alloy for treating molten iron containing carbon to produce ductile or compacted graphite cast irons which comprises the steps of forming a molten iron bath comprising by weight from about 1.0 to about 6.0% silicon, about 0.2 to about 2.0% rare earth elements pre-dominately cerium, about 0.9 to about 2.0% magnesium, about 3.0 to about 6.0%
carbon, the balance being iron, maintaining said molten bath under from about 50 to about 75 p.s.i.g. pressure of an inert gas while reaction takes place and adjusting the proportions of said metals to produce the iron alloy with density from about 6.5 to about 7.5 gms/cm.3
carbon, the balance being iron, maintaining said molten bath under from about 50 to about 75 p.s.i.g. pressure of an inert gas while reaction takes place and adjusting the proportions of said metals to produce the iron alloy with density from about 6.5 to about 7.5 gms/cm.3
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US362,866 | 1982-03-29 | ||
| US06/362,866 US4472197A (en) | 1982-03-29 | 1982-03-29 | Alloy and process for producing ductile and compacted graphite cast irons |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1217361A true CA1217361A (en) | 1987-02-03 |
Family
ID=23427819
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000424042A Expired CA1217361A (en) | 1982-03-29 | 1983-03-21 | Alloy and process for producing ductile and compacted graphite cast irons |
Country Status (12)
| Country | Link |
|---|---|
| US (1) | US4472197A (en) |
| EP (1) | EP0090654B1 (en) |
| JP (1) | JPS58174516A (en) |
| AR (1) | AR231548A1 (en) |
| AT (1) | ATE34410T1 (en) |
| AU (1) | AU1296183A (en) |
| BR (1) | BR8301562A (en) |
| CA (1) | CA1217361A (en) |
| DE (1) | DE3376661D1 (en) |
| FI (1) | FI830852L (en) |
| MX (1) | MX157413A (en) |
| PT (1) | PT76435B (en) |
Families Citing this family (12)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3409550C1 (en) * | 1984-03-15 | 1985-06-20 | Ingenieurbüro Dr.-Ing. Karl Ableidinger & Dr.-Ing. Hans Heyer, Zürich | Inoculating alloy for the production of spherulitic cast iron |
| CH660027A5 (en) * | 1984-04-13 | 1987-03-13 | Fischer Ag Georg | METHOD AND MEANS FOR PRODUCTION OF A CAST IRON WITH VERMICULAR GRAPHITE. |
| CH660376A5 (en) * | 1984-07-26 | 1987-04-15 | Fischer Ag Georg | METHOD FOR PRODUCING CAST IRON WITH BALL GRAPHITE. |
| US4596606A (en) * | 1984-09-04 | 1986-06-24 | Ford Motor Company | Method of making CG iron |
| US4737199A (en) * | 1985-12-23 | 1988-04-12 | Ford Motor Company | Machinable ductile or semiductile cast iron and method |
| US4999158A (en) * | 1986-12-03 | 1991-03-12 | Chrysler Corporation | Oxidation resistant iron base alloy compositions |
| RU2156810C1 (en) * | 2000-01-21 | 2000-09-27 | Общество с ограниченной ответственностью "Экономист" | Method for making high strength cast iron with spheroidal and vermiculite type graphite |
| RU2156809C1 (en) * | 2000-01-21 | 2000-09-27 | Общество с ограниченной ответственностью "Экономист" | Method for making high strength cast iron |
| DE10037359A1 (en) * | 2000-07-31 | 2002-02-21 | Babcock Gieserei Gmbh | Heavily loaded spheroidal casting part cast from a base melt consists of crude iron, steel briquettes and recycled material, nickel, a cerium/silicon mixture, a bismuth/silicon mixture, manganese, phosphorus, and sulfur |
| RU2188240C1 (en) * | 2001-04-19 | 2002-08-27 | Рушаник Борис Авсеевич | Method of high-strength cast iron production |
| WO2008112720A1 (en) * | 2007-03-12 | 2008-09-18 | Wescast Industries, Inc. | Ferritic high-silicon cast irons |
| CN109811250B (en) * | 2019-03-01 | 2021-04-20 | 广西玉柴机器股份有限公司 | Method for improving reliability of engine cylinder cover and silicon solid solution strengthened ferrite vermicular graphite cast iron |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB765423A (en) * | 1954-03-06 | 1957-01-09 | Mond Nickel Co Ltd | Improvements in methods of and apparatus for the treatment of molten iron and steel |
| US2792300A (en) * | 1954-04-14 | 1957-05-14 | John A Livingston | Process for the production of nodular iron |
| GB827166A (en) * | 1954-09-03 | 1960-02-03 | William Gray & Company Ltd | Improvements in or relating to iron alloys and to the manufacture of cast iron |
| SE328673B (en) * | 1967-02-10 | 1970-09-21 | Asea Ab | |
| US4147533A (en) * | 1977-07-11 | 1979-04-03 | Flinn Richard A | Process for the production of ferro-magnesium and the like |
| DE2966152D1 (en) * | 1979-03-27 | 1983-10-20 | Flinn Aloysius R | Process and apparatus for the production of metallic compositions comprising at least two constituents, one constituent having a melting temperature exceeding the boiling temperature of the other |
| GB2066297B (en) * | 1979-12-19 | 1984-02-29 | Foseco Int | Vermicular graphite iron production using compacted additive mixture |
-
1982
- 1982-03-29 US US06/362,866 patent/US4472197A/en not_active Expired - Fee Related
-
1983
- 1983-03-15 FI FI830852A patent/FI830852L/en not_active Application Discontinuation
- 1983-03-21 CA CA000424042A patent/CA1217361A/en not_active Expired
- 1983-03-23 PT PT76435A patent/PT76435B/en unknown
- 1983-03-23 AR AR292482A patent/AR231548A1/en active
- 1983-03-25 BR BR8301562A patent/BR8301562A/en not_active IP Right Cessation
- 1983-03-28 MX MX196745A patent/MX157413A/en unknown
- 1983-03-28 JP JP58050568A patent/JPS58174516A/en active Pending
- 1983-03-29 AU AU12961/83A patent/AU1296183A/en not_active Abandoned
- 1983-03-29 EP EP83301778A patent/EP0090654B1/en not_active Expired
- 1983-03-29 AT AT83301778T patent/ATE34410T1/en not_active IP Right Cessation
- 1983-03-29 DE DE8383301778T patent/DE3376661D1/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| US4472197A (en) | 1984-09-18 |
| PT76435A (en) | 1983-04-01 |
| FI830852A7 (en) | 1983-09-30 |
| JPS58174516A (en) | 1983-10-13 |
| EP0090654A2 (en) | 1983-10-05 |
| BR8301562A (en) | 1983-12-06 |
| ATE34410T1 (en) | 1988-06-15 |
| AU1296183A (en) | 1983-11-03 |
| PT76435B (en) | 1985-12-09 |
| EP0090654A3 (en) | 1984-03-07 |
| MX157413A (en) | 1988-11-22 |
| EP0090654B1 (en) | 1988-05-18 |
| AR231548A1 (en) | 1984-12-28 |
| FI830852L (en) | 1983-09-30 |
| DE3376661D1 (en) | 1988-06-23 |
| FI830852A0 (en) | 1983-03-15 |
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